1. Field of the Invention
The present invention relates to an optical measurement apparatus, in particular to an optical measurement apparatus in which an illuminating light is irradiated to the sample in order to measure optical information of the sample dispersed in the liquid flowing through the flow passage.
2. Description of the Related Art
It is proposed that optical information (fluorescent information) of the sample in the liquid flow is measured in which the liquid with the sample dispersed therein flows in the capillary and the light from the light source is irradiated to the liquid flow (refer to Japanese Patent No. 2973387).
In the measurement apparatus disclosed in the Japanese Patent No. 2973387, a laser light is irradiated through the optical fiber to the sample passing through the capillary. However, the end face of the optical fiber is placed in close to the surface of the capillary. Accordingly, the air layer is formed in the interface between the end face of the optical fiber and the surface of the capillary.
Since the refractive indexes in the optical fiber to the air layer, and the air layer to the capillary are different, the optical loss of the irradiated light from the end face of the optical fiber to the capillary is caused to make it difficult to measure the sampling with high sensitivity.
Measured value dispersion varies depending on the irradiated area to the range of the flowing sample, the adjustment in the interrelation is important.
One of the object of the invention is to provide an optical measurement apparatus, for overcoming the above described problems, in which the sample is optically measured without loss of the illuminating light with high sensitivity so as to reduce variability in measurement.